化学链燃烧钙基载氧体CaSO_4与CO在不同温度下的反应行为

Reduction of CaSO_4 oxygen carrier with CO in chemical-looping combustion

基于热重和红外联用进行等温实验,探讨了化学链燃烧载氧体CaSO4在CO气氛下的还原反应特性。研究发现:温度对CaSO4还原反应历程和速率有显著的影响,在10%CO气氛下,温度低于900℃时,发生单一反应,CaSO4的还原产物只是CaS,气相产物为CO2;当温度高于950℃后,发生平行反应和连串反应组合成的多重反应,固体产物为CaS和CaO,而产物气中除了有CO2,还存在SO2和COS,且气相硫化物的析出以COS为主;随着反应温度的升高,CaSO4与CO反应速率显著增加,而目标产物CaS在固体产物中所占的摩尔分数呈下降趋势;基于钙基载氧体化学链燃烧中燃料反应器温度不宜高于950℃。

Chemical-looping combustion（CLC）with CaSO4 as oxygen carrier is a novel combustion technology with inherent CO2 separation.Based on the isothermal test with thermogravimetric analyzer（TGA） and Fourier transform infrared（FT-IR） spectrum,the reduction of CaSO4 with CO in a CLC process was discussed in this paper.The experiments showed that reaction temperature had a notable effect on both the reaction course and reaction rate of CaSO4 reduction in the 10% CO atmosphere.When the temperature was below 900℃,there only existed a single reaction,CaSO4 would only be converted into CaS,with CO2 as the gas product.However,when the temperature was above 950 ℃,multiple reactions of parallel reactions and consecutive reactions would take place with the products of CaS and CaO.And the gaseous products would be CO2 as well as SO2 and COS,with the gaseous sulfide mainly in the form of COS.Moreover,with increasing temperature,the rate of the reaction of CaSO4 and CO would apparently increase,but the mole fraction of CaS product in the solid residue tended to decrease.It indicated that the fuel reaction temperature should be below 950℃.